4 OF THE STEM. 
heat enables changes to take place in the seed; and the 
air is necessary to assist these changes. 
4. The radicle or rootlet which the seed pushes out, 
is of a conical or taper form, and always takes a down- 
ward direction, whatever may have been the position 
of the seed when placed in the ground:—while the 
plumule or stem as constantly takes the upward or 
ascending; the former seeks the soil and darkness, and 
is usually white, the latter is greenish and requires 
light and air. The root soon passes from this simple 
form and takes some other (f. 4.) by dividing into a 
number of finer parts; but generally there is a main 
or principal root, and many small ones branching off 
from it, as in the Radish, &e. ach little root or fibre 
of the root ends in a fine point, which enables it to take 
up the moisture, &c. which is in the earth, and which 
is then conveyed to the main stem, through which it is 
carried to the other parts of the plant. If these fine 
points are cut off from a plant, it will die, unless it is 
able to produce more, as the greater part of the nou- 
rishment which the plant obtains from the earth can 
only pass through these fine parts: hence the necessity 
of great care being taken in the removal of plants from 
one part of a garden to another. 
OF THE STEM GENERALLY. 
5. In proportion as the radicle or rootlet of the young 
plant lengthens and becomes a root with fibres, at the 
same time and to some similar extent does the plumule, 
or ascending portion, assume the form of a stem, and 
all those parts which belong to the stem of a plant. 
